I'm in the process of rebuilding a '81 Fiat 2000 FI and I plan on putting an 1800 port/polished head w/stock cams on the original bottom end. I'm new to the rebuild process and my reading so far suggests that I need to take into account total compression when determining what piston CR I should choose. So, with the 1800 head as noted above, what is my upper CR limit for the pistons and the engine overall? Forged over cast pistons - correct?